CVE-2018-6558 — The pam_fscrypt module in fscrypt before 0

The pam_fscrypt module in fscrypt before 0.2.4 may incorrectly restore primary and supplementary group IDs to the values associated with the root user, which allows attackers to gain privileges via a successful login through certain applications that use Linux-PAM (aka pam).

01What is this vulnerability?

The pam_fscrypt module in fscrypt before 0.2.4 may incorrectly restore primary and supplementary group IDs to the values associated with the root user, which allows attackers to gain privileges via a successful login through certain applications that use Linux-PAM (aka pam).

02Affected products

Vendor	Product	Versions
The fscrypt Project	fscrypt	before 0.2.4

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2018-08-23T20:00:00.000Z
• Last modified: 2024-09-17T02:06:50.219Z

09References

• github.com — https://github.com/google/fscrypt/issues/77
• github.com — https://github.com/google/fscrypt/commit/3022c1603d968c22f147b4a2c49c4637dd1be91…
• github.com — https://github.com/google/fscrypt/commit/315f9b042237200174a1fb99427f74027e191d6…
• launchpad.net — https://launchpad.net/bugs/1787548